1. Field of the Invention
The present invention relates to techniques for assessing the level of protection afforded by chemical resistant gloves and other protective clothing or equipment.
2. Description of the Prior Art
Health and safety organizations in the United States and foreign countries have historically regulated the allowable "safe" levels of chemical exposure in the workplace. Hundreds of compounds are variously listed in these countries with a "skin" designation which indicates the potential for considerable damage to the skin and/or systemic toxicity via dermal absorption. Accordingly, personal protective clothing and equipment is an important segment of safety in the workplace. One of the most common types of protective clothing is gloves designed to be resistant to contaminant chemicals of interest.
To date, the choice of chemical protective gloves and clothing has been based on laboratory testing of chemical breakthrough of the material of construction in accordance with test procedures specified by the American Society of Test Methods ("ASTM"). The ASTM distinguishes between "penetration", which it defines as the flow of a chemical through closures, porous materials, seams and pin holes or other imperfections in protective clothing material on a nonmolecular level, and "permeation", which it defines as the movement of a chemical through protective clothing material on a molecular level. The term "breakthrough" will be used herein as a generic designation encompassing both penetration and permeation. The ASTM test procedures specify that the protective material be tested for continuous exposure to the chemical or solvent system of interest. Such a test protocol is not a realistic representation of most field work situations, where chemical or solvent exposure most typically occurs on an intermittent and/or short-term basis. The result is that gloves or other protective clothing which pass the ASTM protocol for the chemical of interest are frequently overdesigned, i.e., they are much more resistant to the contaminant chemical of interest than is necessary for the particular field use application, and/or they are replaced much more frequently, in accordance with the protocol, than is necessary. This is costly and wasteful, since protective gloves and other clothing may be quite expensive to manufacture.
Another difficulty is that certain government regulations require the testing of gloves and other protective clothing to be based on the expected conditions of exposure, including the likely combinations of chemical substances to which the clothing may be exposed in the workplace, in order to establish that the clothing would be impervious for the expected duration and conditions of exposure. This required effectiveness of chemical protective clothing and gloves against combinations of chemical substances has been very difficult to ascertain in actual field use conditions. Thus, for example, protective gloves are made in a wide variety of different materials and different thicknesses for protection against different chemicals, and a glove which offers excellent protection for one chemical or group of chemicals may be completely unsuitable for protecting against a different chemical or group of chemicals. Prior efforts to measure chemical breakthrough of protective gloves and clothing have used cotton or cellulose pads attached under the gloves or clothing of absorb chemicals which break through the protective material. These pads are then analyzed in a laboratory to determine whether any breakthrough has occurred and, if so, to identify which chemicals have broken through the protective clothing. Then, the glove formulation is changed to one which is more protective against the penetrating chemical or chemicals and the test is repeated. But the requirement for laboratory testing to determine whether any breakthrough has occurred results in a significant additional expense, since laboratory analysis must be done every time.